In a typical cellular radio system, “wireless” user equipment units (UEs) and one or more “core” networks (like the public telephone network or Internet) communicate via a radio access network (RAN). The UEs very often are mobile, e.g., cellular telephones and laptops with mobile radio communication capabilities (mobile terminals). UEs and the core networks communicate both voice and data information via the radio access network.
The radio access network services a geographical area which is divided into cell areas, with each cell area being served by a base station (BS). Thus, a base station can serve one or multiple cells. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by a unique identity, which is broadcast in the cell. Base stations communicate over a radio or “air” interface with the user equipment units. In the radio access network, one or more base stations are typically connected (e.g., by landlines or microwave links) to a radio network controller (RNC). The radio network controller, also sometimes termed a base station controller (BSC), supervises and coordinates various activities of its base stations. In turn, the radio network controllers are typically coupled together and coupled to one or more core network service nodes which interface with one or more core networks.
One example of a radio access network is the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN). The UTRAN is a third generation system which in some respects builds upon the radio access technology known as Global System for Mobile communications (GSM) developed in Europe. URAN is a wideband code division multiple access (W-CDMA) system.
A goal of the Third Generation Partnership Project (3GPP) is to evolve further the UTRAN and GSM-based radio access network technologies. Of particular interest here is the support of variable transmission rate services in the third generation mobile radio communications system for both real time and non-real time services. Of course, since all users share the same radio resources, the radio access network must carefully allocate resources to individual UE connections based on quality of service requirements, such as variable rate services, and on the availability of radio resources. When a core network desires to communicate with a UE, it requests services from the radio access network in the form of radio access bearers (RABs) with a particular quality of service (QoS). Quality of service includes such things as data rates, speed, variability of data rate, amount and variability of delay, guaranteed versus best effort delivery, error rate, etc. A radio access bearer is a logical channel or connection through the UTRAN and over the radio interface corresponding to a single data stream. For example, one bearer carries a speech connection, another bearer carries a video connection, and a third bearer carries a packet data connection. Connections are mapped by the UTRAN onto physical transport channels. By providing radio access bearer services to the core network, the UTRAN isolates the core network from the details of radio resource handling, radio channel allocations, and radio control, e.g., soft handover. For simplicity, the term “connection” is used hereafter.
If during the lifetime of the connection, the UE moves to a cell controlled by another RNC, (referred to as a drift RNC (DRNC)), then the RNC that was initially set up to handle the connection for the UE, (referred to as the serving RNC (SRNC)), must request radio resources for the connection from the drift RNC over an Iur interface. If that request is granted, a transmission path is established for the connection between the SRNC and the DRNC to the UE through a base station controlled by the DRNC. A UE whose connection has been handed over from a SRNC to a DRNC is referred to as a drifting UE (DUE). In contrast, when the UE connection is currently serviced by a cell under the control of the SRNC, such a UE is referred to as a non-drifting UE (NDUE).
In most networks, it is desirable to monitor the performance of the network by gathering various statistics, measurements, and other data from the network, processing it, and generating some sort of performance report. Of course, performance can be measured in a variety of ways. Some examples include measuring or determining the volume of traffic, number of attempted, successful, and/or failed connections, number of attempted, successful, and/or failed radio link additions and/or deletions per cell, power levels, interference levels, lost calls, congestion statistics, call setup and tear down times, heavy and light use time frames, number of attempted, successful, and/or failed handovers (hard or inter-radio access technology), etc.
In order to generate these kinds of performance management statistics, the network management system requires measurements and other data to be provided from the network. That information typically must be formatted and communicated using a format and protocol understood by the management system. In modern communication networks, management/statistics functions are performed using a managed information model that is based on managed objects. Observations of the instances of each managed object are stored in a management information database and then provided, typically as a file, to the management system. Performance information for UE-related functions are often specified to be measured and reported per cell.
The management system typically employs formatting and identification schemes that are not the same as those used in the radio access network. For example, each managed object in the management system may be identified by a local distinguished name (LDN) or other managed object identifier. In order to identify a particular object, such as a particular cell, the LDN for that cell or other object identifier must be known. Unfortunately, managed object identifiers, like LDNs, are only used by the management system, and not by the radio access network such as a UTRAN. In a UTRAN, for example, information is identified using cell identifiers and UE identifiers, and not by using managed object identifiers like LDNs. Thus, when an RNC is to report to the management system a particular observation, e.g., maximum allowed downlink power, for a particular managed object cell controlled by that RNC, the observation value is sent along with the LDN for that cell. This information is in a format that can be understood by the management system.
Cells controlled by other RNCs have different managed object identifiers. When a connection is handed over from a serving RNC to a drift RNC, the serving RNC is still in control of the handed-over connection and is the only RNC aware of certain procedures regarding the UE. The drift RNC is a “dumb” node and simply provides radio resources for that connection without having any control of the drifting UE that is now being serviced by one of its cells. In other words, one of the cells in the DRNC's area is servicing a drifting UE connection, but the drift RNC is not aware of everything that happens to it, and therefore, will not be able to report all drifting UE information to the network management system. The serving RNC also cannot report such drifting UE information (that is not known in the drift RNC) to the management system because the cells controlled by the drift RNC area are identified with a managed object identifier that is not known in the serving RNC. Only the drift RNC can report information about managed objects within its control. However, the drift RNC is not “aware” of everything that happens to drifting UEs whose connections are controlled by another RNC.
Although RNCs communicate traffic information to each other, they do not communicate management information to each other. As a result, an RNC is only aware of its own LDN and the LDNs of its underlying managed objects, e.g., its cells. The RNC is not aware of the LDNs of other RNCs or their managed objects. One way of overcoming this problem is to introduce additional control signaling between RNCs for management purposes. For example, when a connection is handed over from a serving RNC to a drift RNC, the serving RNC would send, in addition to the handover traffic information, information, like service type and handover result, which could be used to monitor performance in drifting RNC cells. With this management information, the drift RNC becomes an “intelligent” node capable of reporting management information for the drifting UE. A disadvantage of this approach is that it requires increased signaling between RNCs and a reworking of the RNC Iur interface.
A second solution is for each drift RNC to broadcast management information about all of its managed objects to serving RNCs. Each serving RNC stores and updates managed object information for all cells for all other RNCs. However, this large amount of management information exchange, storage, and data processing is undesirable.
A third approach is to report management information using radio network-type identifiers such as cell identifiers and RNC identifiers. The serving RNC is aware when a connection is handed over to a particular cell associated with a particular RNC. The serving RNC provides this information to the management system using the radio traffic-based identification format. A downside with this approach is that the management system must translate the radio traffic-based information and identifiers into management-based information and identifiers to comply with standards and align to other management functions.
The above approaches require modification of existing management/performance reporting formats, protocols, and procedures as well as additional signaling and/or processing load. The present invention offers a better solution that works within current system frameworks and does not increase signaling and processing burdens. The level of drifting UEs in a particular cell is determined based on established radio links in the cell. Existing management information for non-drifting UEs is used to estimate similar information for drifting UEs using the determined level of drifting UEs. Management information for both drifting and non-drifting UEs is reported to the management system using existing management system formats, protocols, and procedures.
In the context of a cellular radio communications system that includes a first radio network controller (RNC) coupled to several first cells, the first RNC performs a number of procedures in order to report management information for drifting mobile radios in the first cells coupled to the first RNC. Drifting mobile radios having connections handed over to one of the first cells are monitored. Management information for drifting mobile radios in the one cell is determined and reported to a management node or system. One example way of determining management information for drifting mobile radios is to determine a percentage of radio links established for non-drifting mobiles relative to the number of radio links established for drifting mobiles in a particular cell. That percentage is used to scale the non-drifting UE management information to estimate corresponding drifting UE management information. Both sets of information are provided to the management node so that both drifting mobile radios and non-drifting mobile radios in a cell are taken into account in management statistics and analysis.
The reporting may be performed using an existing management protocol over a management protocol interface between the first RNC and the management node. If the management protocol uses managed objects, each managed object may be identified in the management protocol using a Local Distinguishing Name (LDN). If each cell is a managed object having a corresponding LDN, a report to the management node includes an LDN for the managed object cell. If each RNC is a managed object having a corresponding LDN, the report to the management node includes an LDN for a managed object RNC.